FIG. 1 illustrates a network structure of an evolved universal mobile telecommunications system (E-UMTS) which is a mobile communication system.
The E-UMTS is a system evolved from the existing UMTS and a basic standardization thereof is currently being performed in the 3GPP. The E-UMTS may be called a long term evolution (LTE) system.
The E-UMTS network may be largely classified into a UMTS terrestrial radio access network (E-UTRAN) and a core network (CN). The E-UTRAN includes a terminal (user equipment: UE), a base station (eNode-B or eNB), a serving gateway (S-GW) which is located at an end of the network and is connected to an external network, and a mobility management entity (MME) for managing mobility of the terminal. One ore more cells may exist for a single base station.
FIGS. 2 and 3 illustrate the structure of a radio interface protocol between the terminal and the base station based on the 3GPP radio access network standard.
The radio interface protocol is horizontally divided into a physical layer PHY, a data link layer and a network layer and is vertically divided into a user plane for transmitting data information and a control plane for transmitting control signaling. FIG. 2 shows layers of the radio protocol control plane and FIG. 3 shows the layers of the radio protocol user plane.
The protocol layers may be divided into a first layer (L1), a second layer (L2) and a third layer (L3) based on the three lower layers of an open system interconnection (OSI) standard model which is well-known in the art of communication systems.
The PHY layer, which is the first layer, provides an information transfer service to an upper layer by using a physical channel. The PHY layer is connected with a medium access control (MAC) layer located at a higher level through a transport channel, and data between the MAC layer and the PHY layer is transferred via the transport channel. Between different physical layers, namely, between PHY layers of a transmission side and a reception side, data is transferred via the physical channel.
The MAC layer of the second layer provides services to a radio link control (RLC) layer, which is a higher layer, via a logical channel. The RLC layer of the second layer supports the transmission of data with reliability. The function of the RLC layer may be implemented by a functional block within the MAC layer. In this case, the RLC layer may not exist.
The PDCP layer of the second layer performs a header compression function that reduces the size of an Internet protocol (IP) packet header containing unnecessary control information having a relatively large size in order to efficiently transmit the IP packets such as IPv4 or IPv6 over a radio interface having a small bandwidth.
A radio resource control (RRC) layer located at the highest portion of the third layer (L3) is only defined in the control plane and controls logical channels, transport channels and the physical channels in relation to the configuration, reconfiguration, and release of the radio bearers (RBs). Here, the RB signifies a service provided by the second layer for data transmission between the terminal and the UTRAN.
FIG. 4 illustrates an example of a method for allowing the terminal to receive data in the E-UMTS.
The base station and the terminal may mostly transmit/receive data via a downlink shared channel (DL-SCH) as a transport channel and a physical downlink shared channel (PDSCH) as a physical channel, except for a specific control signal or specific service data. At this time, data transmitted via the PDSCH is transmitted to one or more terminals, and information indicating how the terminals receive the data via the PDSCH and decode the data may be transmitted via a physical downlink control channel (PDCCH) as a physical channel.
If the control information of the plurality of terminals is transmitted together, the control information may be identified using an identifier in order to identify the control information of each of the terminals. For example, it is assumed that a specific PDCCH, in which a cyclic redundancy check (CRC) is masked with a radio network temporary identifier (RNTI) “A” and information about data which is being transmitted with transport format information “C” (e.g., a transport block size, modulation, coding information and so on) via a radio source “B” (e.g., frequency position) is included, is transmitted in a specific sub-frame. The RNTI with which the CRC is masked in the specific PDCCH may be transmitted via as described above. Or, The RNTI may be transmitted in a state of being included in the PDCCH.
In this case, one or more terminals located in a cell monitor the PDCCH using its RNTI information and receive the PDCCH if one or more terminals having the RNTI A exist at that time. At this time, the PDSCH indicated by the B and C may be received via the received PDCCH.
In the above-described process, in order to report to which terminal allocation information of the radio resource transmitted via the PDCCH corresponds, an identifier, e.g., a RNTI, is transmitted. The RNTI includes a dedicated RNTI and a common RNTI. The dedicated RNTI is used for transmission/reception of data to a specific terminal and is used when the information of the terminal is registered in the base station.
In contrast, the common RNTI is used for transmission of information which is commonly used by the plurality of terminals, such as system information, or for transmission/reception of data to/from terminals which are not allocated with dedicated RNTIs because the information of the terminals is not registered in the base station. For example, in a random access channel (RACH) process, a random access RNTI (RA-RNTI) or T-C RNTI may correspond to the common RNTI.